Metal dienyl gas plating



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iii-L Patent METAL DIENYL GAS PLATIN G Jack .I. Bullotf, Columbus, Ohio,assignor to The Commonwealth Engineering Company of Ohio, Dayton, OhioNo Drawing. Application January 16, 1957 Serial No. 634,410

12 Claims. (Cl. 117107) This invention relates to the art of depositionof metals, and more particularly to the plating of objects by thedeposition of metal from readily decomposable volatile metal bearingcompounds and commonly referred to as gas plating.

Heretofore deposition of metals has been accomplished utilizing aheat-decomposable volatile compound of the metal to be deposited. Gasplating of metals which form carbonyls, alkyls, aryls and aralkyls hasthus been carried out employing these metal bearing compounds.

The plating of metals which do not readily form carbonyls, alkyls oraryls as aforementioned, has been difficult to accomplish. Furthermore,the use of gaseous decomposable metal alkyls or aryls requires carefulhandling and exacting controls to avoid explosion, especially when gasplating in the presence of air, oxygen, water vapor or oxygenic gasesoften used for conditioning deposits. In addition, it is desirable toemploy metal bearing compounds which are intrinsically less poisonous inuse than the gaseous carbonyls. The present invention overcomes thesedisadvantages by the use of dienyl metal bearing compounds for gasplating.

It is accordingly an object of the present invention to deposit metal,metal carbide or carbide metal phases on suitably heated substrates bythe use of a relatively cool vapor of a metal diene compound.

It is a further object of the invention to provide a method of gasplating metals which do not readily form organo alkyl and aryl compoundsor metal carbonyls such as titanium, vanadium, and the like.

It is a further object of the invention to provide a method andapparatus for gas plating metals using dienyl heat decomposable metalbearing compounds which are decomposable at relatively low temperaturesand which disassociate to deposit the metal constituent on substrates.

These and other objects and advantages will become more apparent in viewof the following description.

Briefly, the invention comprises carrying out gas plating wherein theworkpiece or substrate to be plated with metal is heated to atemperature sufficient to cause decomposition of a volatile metalbearing dienyl compound brought in contact therewith. The inventionbroadly concerns the use in gas plating of compounds of the classillustrated by the structural formula and substitution compounds thereofsuch as where R R and R may be hydrogen or an alkyl-group or acombination thereof.

Further the invention contemplates the use of metal bearing compoundswhich possess atleast three carbons and contain diene structure.

Examples of such compounds are the metal dicyclopentadienides, themetalloid polycyclopentad-ienyl compounds, and the triandtetra-cyclopentadienides, and their indenide and other congeners.

In carrying out the process the article or substrate to be gas plated ispreferably placed in an enclosure and the air removed therefrom as bythe use of a vacuum pump, and the article heated to a temperaturesuificientto cause decomposition of the gaseous metal bearing dienylcompound introduced into the enclosure and brought in contact with theheated article.

The following examples are illustrative but not limitative of how theprocess of the invention may be carried out.

Example I An iron wire is heated to red heat (500-700 C.) in a bell jarwith the air removed by vacuum, to a pressure of 3 millimeters mercuryand the atmosphere of the bell jar replaced with gaseous manganesecyclopentadienyl. Upon subjecting the heated wire for 3 minutes to theplating atmosphere it was found that the wire was coated with a film ofmanganese metal and Mn C.

Example 11 Copper wire was heated by electrical induction similarly asin Example II to red heat (500-700 C.) and the heated copper rodsubjected to gaseous titanium biseyclopentadienyl whereby the same iscoated with titanium metal and titanium carbide.

Example IV The article comprises a rod of thorium metal which is heatedto approximately 800 F. and contacted with magnesium dicyclopentadienideto deposit a thin film of magnesium metal thereon.

The metal bearing compounds found useful are the.

metals which form cyclopentadienides, especially the metals of group IIand III of the periodic table, e.g., Be, Al, La, Lu.

Example V In this instance the gas plating is carried out as describedin Example I, using gaseous vanadium biscyclopentadienyl to depositvanadium.

Also metals which form biscyclopentadienyls such as those found ingroups IV, V, VI, VII and VIII of .the

periodic table, such as Ti, V, Cr, Re, Fe, Co, Ni, Ru. Manganese formsthe biscyclopentadiene. Also metals of group Ia, IIa, IIIa, IVa and Va,the metalloids of those groups which form polypentadienyls, for exampleM(C H where x is the valence for example of Si, Ge and Sb.

In accordance with my invention, a process is provided for gas platingof metals by employing metal hearing compounds which do not containoxygen, use being made of poly-enyl compounds of both open-chain andcyclic molecular structures. The metal-organic compounds best suited forgas plating contain at least three carbon atoms and up to five in thebasic molecular structure with at least two unsaturated (C C) groupingsin the molecule. Vaporized metal bearing compounds se lected from thegroup consisting of cyclopentadienides, biscyclopentadienyls,biscyclopentadienides, and polypentadienyls being utilized as the gasplating medium. The metal plating gas may be used with or withoutcarrier gas, e.g., argon, nitrogen, as is conventional in this art.

When it is desired carrier gas may be utilized together with the dienylmetal bearing gaseous compounds, particularly where the metal vapors areto be passed through a system as when gas plating a continuously movingstrip, filament or sheet. Each substrate or material which is to beplated will be heated to the proper temperature, which temperaturedepends upon the metal bearing dienyl compound used. Each of such metalcompounds has a temperature at which it decomposes. This varies over arange, but in general temperatures between 300-1000 C. may be utilizedto effect the gas plating with the dienyl metal bearing compounds.

Mixtures of these dienyl metal bearing compounds may be used to deposita combination of the metals or alloys as desired. Further, after coatingthe substrate the resultant metal coated product may be annealed or heattreated as may be desired. Such annealing may also be carried out in aninert atmosphere where oxidation of the newly deposited metal coating isundesirable.

It will be understood that while the method and apparatus disclosed anddescribed herein illustrate a preferred form of the invention and how itcan be carried out, modifications obviously may be made by those skilledin the art without departing from the spirit and scope of this inventionand all such modifications that fall wtihin the disclosure and scope ofthe appended claims are intended to be included herein.

What is claimed is:

1. In a process of gas plating wherein the substrate to be plated isheated to a temperature sufficient to cause decomposition of a volatilemetal compound brought in contact therewith, the step of bringing agaseous metal bearing poly-enyl compound in contact with said substratewhile the latter is heated above the decomposition temperature of saidcompound and under a non-oxidizing atmosphere to cause decomposition ofthe gaseous metal compound and deposition of metal onto the surface ofthe substrate.

2. In a process of gas plating wherein the substrate to be plated isheated to a temperature sufiicient to cause decomposition of a volatilemetal compound brought in contact therewith, the step of bringing agaseous metal bearing dienyl compound containing at least three carbonsin its molecular structure in contact with said substrate while thelatter is heated above the decomposition temperature of said compoundand under a non-oxidizing atmosphere to cause decomposition of thegaseous metal compound and deposition of metal onto the surface of thesubstrate.

3. In a process of gas plating wherein the substrate to be plated isheated to a temperature sufiicient to cause decomposition of a volatilemetal compound brought in contact therewith, the step of bringing agaseous metal bearing poly-enyl compound in contact with said substratewhile the latter is heated above the decomposition temperature of saidcompound and under a non-oxidizing atmosphere to cause decomposition ofthe gaseous metal compound and deposition of metal onto the surface ofthe substrate, said poly-enyl compound being selected from the groupconsisting of cyclopentadienides, biscyclopentadienyls,biscyclopentadienides and polypentadienyls.

4. A process of gas plating substrate as in claim 1, wherein said metalbearing compound consists of a metal dienyl compound containing at leasttwo carbons in the molecule.

5. A process of gas plating substrate as in claim 1, wherein said metalbearing compound consists of a metal dienyl compound containing apoly-enyl molecular structure.

6. A process of gas plating substrate as in claim 1, wherein said metalbearing compound consists of a metal diene of the metals of group Ia,Ila, IIIa, IVa, and Va.

7. A process of gas plating manganese onto a substrate which comprisesheating the substrate to 500-700 C. under a non-oxidizing atmosphere,and subjecting the thus heated substrate to gaseous manganesecyclopentadienyl to cause decomposition of the manganese diene anddeposition of manganese onto the surface of said substrate.

8. A process of gas plating titanium onto a substrate which comprisesheating the substrate to SOD-700 C. under a non-oxidizing atmosphere,and subjecting the thus heated substrate to gaseous titaniumbiscyclopentadienyl to cause decomposition of the titanium diene anddeposit1on of titanium onto the surface of said substrate.

9 A process of gas plating magnesium onto a substrate which comprisesheating the substrate to 500-700 C. under a non-oxidizing atmosphere,and subjecting the thus heated substrate to gaseous magnesiumdicyclopentadiemde to cause decomposition of the magnesium diene anddeposition of magnesium onto the surface of said substrate.

10. A process of gas plating vanadium onto a substrate which comprisesheating the substrate to 500-700 C. under a non-oxidizing atmosphere,and subjecting the tons heated substrate to gaseous vanadiumbiscyclopentadienyl to cause decomposition of the vanadium diene anddeposition of vanadium onto the surface of said substrate.

11. A process of gas plating a substrate to deposit a layer of metalcarbide thereon consisting of heating the substrate to 500700 C. in anon-oxidizing atmosphere and thereafter bringing vaporous metalcyclopentadienyl in contact therewith to deposit a coating of metalcarbide thereon.

12. A process of gas plating a substrate to deposit a layer of metalcarbide of titanium thereon consisting of heating the substrate to500-700" C. in a non-oxidizin" atmosphere and thereafter bringingvaporous metal tita: mum biscyclopentadienyl vapor in contact therewithto deposit titanium carbide onto the substrate.

References Cited in the file of this patent UNITED STATES PATENTS2,063,596 Feiler Dec. 8, 1936 2,638,423 Davis et a1. May 12, 1953FOREIGN PATENTS 724,799 Great Britain Feb. 23, 1955

1. IN A PROCESS OF GAS PLATING WHEREIN THE SUBSTRATE TO BE PLATED ISHEATED TO A TEMPERATURE SUFFICIENT TO CAUSE DECOMPOSITION OF A VOLATILEMETAL COMPOUND BROUGHT IN CONTACT THEREWITH, THE STEP OF BRINGING AGASEOUS METAL BEARING POLY-ENYL COMPOUND IN CONTACT WITH SAID SUBSTRATEWHILE THE LATTER IS HEATED ABOVE THE DECOMPOSITION TEMPERATURE OF SAIDCOMPOUND AND UNDER A NON-OXIDIZING ATMOSPHERE TO CAUSE DECOMPOSITION OFTHE GASEOUS METAL COMPOUND AND DEPOSITION OF METAL ONTO THE SURFACE OFTHE SUBSTRATE.